1. Field of the Invention
The present invention relates to liquid crystal displays and a method of manufacturing the same. More particularly, the present invention relates to liquid crystal displays that have electrode arrays for applying electric fields parallel to substrates and thin film transistors as switching elements and a method of manufacturing the same.
2. Description of the Related Art
A liquid crystal display (LCD) having an electrode array for generating an electric field parallel to substrates (IPS mode; in-plane switching mode) is disclosed in U.S. Pat. No. 5,598,285 to Kondo et al.
The IPS mode LCD of Kondo et al. has two substrates opposite each other and a liquid crystal layer therebetween. Two kinds of electrodes for generating an electric field, common electrodes and pixel electrodes, are formed on one of the substrates. An alignment layer is coated on the electrodes.
However, since dielectric layers as a gate insulating layer or passivation layer, which are made of oxide or nitride, are formed on the common electrodes and the pixel electrodes, a potential difference is generated between the electrodes and the alignment layer. As a result, the effective voltage applied to the liquid crystal layer is decreased, and an afterimage appears due to a decrease in the effective voltage. Accordingly, a high driving voltage is required to drive the liquid crystal.
Also, since the two kinds of electrodes are made of different layers and have different thicknesses, the surface of the alignment layer may not be flat, causing non-uniform rubbing which may result in the light leakage.